A micro-cantilever, with the advantages of high sensitivity, fast response, small size, mass production and real-time measurement etc, has been widely used in measurement fields such as chemistry, physics and biology. The micro-cantilever has two operation modes, static and dynamic. The former is achieved by mainly measuring the deflection at an end of the cantilever, and used for such as measuring surface stress, concentration of a substance, etc. The latter is achieved by mainly measuring the resonant frequency of the cantilever in working environment, and used for such as measuring molecular weight of an organism, fluid viscosity and density, etc. The peizoresistive micro-cantilever, without the need of alignment, which is necessary for an optical cantilever, can integrate a detection system upon the cantilever so as to significantly reduce the size of the measurement device. Thus, the peizoresistive micro-cantilever is widely used in Micro-Electro-Mechanical Systems. To measure the density of a fluid with a peizoresistive micro-cantilever, there is a need to acquire the resonant frequency of the cantilever in fluid to be detected. This greatly increases measurement time (more than one minute), and is not suitable for the on-site fluid density measurement, in particular for those fluids that need real time monitoring.
In view of the above disadvantages, there is a need to provide a method of on-line rapid fluid density measurement using a piezoresistive micro-cantilever, so as to reduce measurement time.